Delay line structure



June 4, 1968 w. SOBOTKA DELAY LINE STRUCTURE Filed Aug. 14, 1962 FIG?) FIG.2

4 FIGS FIG.4

vamoa; 505mm ATTORNEY FlG.6

United States Patent 0 20 Claims. (Cl. 333-31 The present invention relates to delay lines for hyperfrequency traveling wave tubes, particularly for those tubes which operate over a relatively wide band of relatively short wave lengths, and intended to supply a relatively large C.W. (continuous wave) power.

It is known that, when it is a question of realizing a tube operating on relatively short wave lengths, the study and examination of the delay line circuit thereof normally ends up with a very small pitch value, while the dimensions of the elements in this delay circuit in the longitudinal direction of the line are naturally even smaller than this pitch.

Added thereto is the condition of large band-width which imposes a circuit of low dispersion. The arrangements known in the prior art of circuits complying with these conditions generally comprise at least in part elements having one or two free ends or extremities, such as the fingers of interdigital lines or bars in the form of a T.

These goemetric conditions namely the smallness of the dimensions in the longitudinal direction and the existence of at least one free end or extremity, determine the slight sturdiness 0r robustness of the elements of the line which buckle or are deformed easily during operation under the effect of the inevitable bombardment of the line by a portion of the electron beam of the tube, and the cooling conditions of which are not favorable, particularly as regards heating of the zones in the neighborhood of the free ends.

Thus, the power of the tube in C.W. operation is limited by the capacity of dissipation of the heat of the delay circuit. I

The present invention aims at the realization of a sturdy and rigid and easily cooled delay line which has, at the same time, a low dispersion within the desired range of short-wave lengths, thus permitting to realize a tube having a wide band and supplying a relatively high CW. power.

The line according to the present invention is of the ladder type, i.e., it comprises bars or rungs having two supported extremities, which increases the sturdiness and rigidity as well as ease of cooling thereof. However, the structures of ladder-type lines known in the prior art present too large a dispersion to allow the realization of a tube with a great band-width.

A line presenting, at the same time, the characteristics of sturdiness and rigidity, ease of cooling thereof, and the desired dispersion is obtained, in accordance with the present invention, by introducing into the structure of a ladder-type delay line a dissymmetry toward the alternately opposed extremities of successive bars.

This dissymmetry may consist of a deformation of one extremity of each rung or bar within the plane of the line so that the deformed extremity approaches or even comes into contact with the non-deformed extremity of an adjacent bar.

Applicants study and tests have indicated that such an arrangement in accordance with the present invention reduces the dispersion with respect to the known laddertype lines.

A further reduction of the dispersion may be achieved by combining this ladder-type structure with a system ICE of vanes or baflies, interposed between the center portions of the bars. r.

These vanes or baflle plates may be secured to or form part of a back plate structure which supports at the same time either the lateral wall portions forming the uprights of the ladder, or the bent ends of the bars.

Accordingly, it is an object of the present invention to provide a delay line structure of the type mentioned hereina bove which eliminates the shortcomings and drawbacks of the prior art constructions by simple means while at the same time improving its operating characteristics for use in hyperfrequency, high-power electron discharge devices.

It is another object of the present invention to provide a wave guiding structure for use in hyperfrequency electron discharge tubes which permits operation over a relatively large band width at relatively very high C.W. power outputs.

Still another object of the present invention resides in the provision of a delay line structure operable at hyperfrequencies which may be readily cooled so as to dissipate the large amounts of heat normally generated therein as a result of the electron bombardment under continuous high-power operation of the tube.

Another object of the present invention resides in the provision of a delay line structure operable at hyperfrequencies which, in addition to the objects and advantages mentioned hereinabove, fulfills the requisite of high sturdiness and rigidity thereby assuring against damage during shipment and installation of the tube as well as against deformation of the delay elements under operating conditions.

These and other objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, two embodiments in accordance with the present invention, and wherein FIGURE 1 is a plan view of a first embodiment of a delay line structure in accordance with the present invention;

FIGURE 2 is a transverse cross-sectional view taken along line IIII of FIGURE 1;

FIGURE 3 is a plan view of a second embodiment of a delay line structure in accordance with the present invention;

FIGURE 4 is a transverse cross-sectional view taken along line lV--IV of FIGURE 3;

FIGURE 5 is'a longitudinal cross-sectional view taken long line V-V of FIGURE 3; and

FIGURE 6 is a diagram illustrating the results obtained with a delay line in accordance with the present invention.

Referring now to the drawing wherein like'reference numerals are used throughout the various views to designate like parts, and more particularly to FIGURES 1 and 2, there is illustrated in these figures a ladder-type line comprising'a plurality of bars or rungs 1, for example, made of cupro-nickel, having each of the two extremities thereof secured to the lateral members or upright portions 2. According to the present invention, a portion adjacent one extremity of each bar or rung 1 is deformed or bent in the plane of the line, alternately to opposed extremities of the successive bars or rungs. Each deformed extremity is thus brought into contact with a non-deformed extremity of an adjacent bar or rung, and the two extremities which are in contact may be welded together. Vanes or battles 3, for example, made of copper, are additionally interposed between the center portions of successive bars or rungs 1. These vanes 0r bafiies are supported by a metallic back-plate 4, for example,

made of copper, which may also support the lateral members or upright portions 2.

The embodiment of FIGURES 3 to S differs from the preceding embodiment only in the fact that the extremities of bars or rungs 1, instead of being secured to the lateral members or upright portions 2, are bent and directly attached to the grooved or ridged back plate 4. The line is thus composed of an alternation of bars or rungs 1 of 1r-Sh'dP6d and of vanes or bafiies 3.

FIGURE 6 shows the dispersion diagram of the fundamental space mode, i.e., curves of the ratio of c/v (c being equal to speed of light, and v being equal to phase velocity of the wave) as a function of the wave length in cm., for two examples, for dimensions of the line according to FIGURES 3 to 5. In the two examples, there has been utilized a 1.5 mm. diameter wire or tubing for the bars or run-gs 1, a line pitch p=3.3 mm. (FIG- URE and a dimension for the baffies 3 of D=47 mm. (FIGURE 4). The curve 5 has been shown for the length of a bar or rung 1 of L=l00 mm. (FIGURE 4) and the curve 6 for a bar or rung 1 of L=80 mm. In the first case, it has been found that the delay line may function in the fundamental space mode at least within the band of wave lengths from 18 to 48 cm., and in the second case, at least between 16 and 32 cm. Atthe same time, the line is sufficiently sturdy and rigid, as the elements thereof do not comprise any free end or extremity, and may be easily cooled by the flow of heat to the solid back plate 4 through the extremities of bars or rungs 1 and through the large base of the vanes or baffles 3. If desired, circulation of a cooling liquid may be established through the tubular bars or rungs 1 appropriately interconnected in series or parallel.

While I have shown and described two specific embodiments in accordance with the present invention, it is obvious that my invention is not limited to the particular examples described hereinabove but is capable of many modifications and variations in the realization thereof as known to a person skilled in the art. The present invention may be realized, for example, both in the rectilinear and in the circular form, and is applicable both to tubes of the O- and of the M-type.

Thus, while I have shown and described two embodiments in accordance with the present invention, it is understood that the same is not limited thereto, but is susceptible of many changes and modifications within the spirit and scope thereof, and I, therefore, do not wish to be limited to the details shown and described herein, but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

I claim:

1. A ladder-type delay line, comprising support means, a series of periodically spaced rungs having both extremities thereof fixed to said support means, the shape of said rungs having, with respect to the plane of longitudinal symmetry of said line, a dissymmetry near one of said extremities in each rung, the dissymmetrical extremities being alternately opposite in successive rungs.

2. A ladder-type delay line, comprising support means, a series of periodically shaped rungs having both extremities thereof fixed to said support means, the shape of said rungs being substantially rectilinear except for the region near one extremity thereof where a respective rung is deformed, the deformations being located alternately near opposite extremities of successive rungs so that the deformed portion of one rung approaches more closely the substantially rectilinear extremity of an adjacent rung than the distance between substantially rectilinear parts of the respective two adjacent rungs.

3. A ladder-type delay line, comprising support means, a series of periodically spaced rungs having both extremities thereof fixed to said support means, the shape of said rungs being substantially rectilinear except for the region near one extremity thereof where a respective rung is deformed, the deformations being located alternately near opposite extremities of successive rungs so that the deformed portion of one rung approaches more closely the substantially rectilinear extremity of an adjacent run-g than the distance between substantially rectilinear parts of the respective two adjacent rungs, the deformed extremity of a respective rung being brought in contact with the substantially rectilinear extremity of the corresponding adjacent rung.

4. A ladder-type delay line, comprising support means, a series of periodically spaced rungs having both extremities thereof fixed to said support means, the shape of said rungs being substantially rectilinear except for the region near one extremity thereof Where a respective rung is deformed, the deformations being located alternately near opposite extremities of successive rungs so that the deformed portion of one rung approaches more closely the substantially rectilinear extremity of an adjacent rung than the distance between substantially rectilinear parts of the respective two adjacent rungs, the deformed extremity of a respective rung being brought in contact with the substantially rectilinear extremity of the corresponding adjacent rung, the deformed and substantially rectilinear extremities of adjacent rungs in contact with each other being soldered together.

5. A ladder-type delay line, comprising support means, a series of periodically spaced rungs having both extremities thereof fixed to said support means, the shape of said rungs having, with respect to the plane of longitudinal symmetry of said line, a dissymmetry near one of said extremities in each rung, the dissymmetrical extremities being alternately opposite in successive rungs, said rungs being made of metallic tubular material to enable the circulation of a cooling medium therethrough.

6. A ladder-type delay line, comprising support means, a series of periodically spaced rungs having both extremities thereof fixed to said support means, the shape of said rungs having, with respect to the plane of longitudinal symmetry of said line, a dissymmetry near one of said extremities in each rung, the dissymmetrical extremities being alternately opposite in successive rungs, and a series of periodically spaced bafiles, each baflie being disposed between two successive rungs.

7. A ladder-type delay line, comprising support means, a series of periodically spaced rungs having both extremities thereof fixed to said support means, the shape of said rungs having, with respect to the plane of longitudinal symmetry of said line, a dissymmetry near one of said extremities in each rung, the dissymmetrical extremities being alternately opposite in successive rungs, and a series of periodically spaced bafi'les, each bafiie being disposed between two successive rungs, said baflies being supported by said support means thereby forming therewith a ridged back plate.

8. A ladder-type delay line, comprising support means having a plane surface, a series of periodically spaced rungs having two extremities bent to be fixed to the plane surface of said support means, the shape of said rungs having, with respect to the plane of longitudinal symmetry of said line, a dissymmetry near one of said extremities in each rung, the dissymmetrical extremities being alternately opposite in successive rungs.

9. A ladder-type delay line, comprising support means including two common lateral support members, a series of periodically spaced rungs having two extremities and each extremity thereof being fixed to a respective common lateral support member of said support means, the shape of said rungs having, with respect to the plane of longitudinal symmetry of said line, a dissymmetry near one of said extremities in each rung, the dissymmetrical extremities being alternately opposite in successive r-ungs.

14). A ladder-type delay line, comprising support means including two common lateral support members fixed to a common back plate, a series of periodically spaced rungs having two extremities and each extremity thereof being fixed to a respective common lateral support member of said support means, the shape of said rungs having, with respect to the plane of longitudinal symmetry of said line, a dissymmetry near one of said extremities in each rung, the dissymmetrical extremities being alternately opposite in successive rungs.

11. A ladder-type delay line, comprising support means including two common lateral support members fixed to a common back plate, a series of periodically spaced rungs having two extremities and each extremity thereof being fixed to a respective common lateral support member of said support means, the shape of said rungs having, with respect to the plane of longitudinal symmetry of said line, a dissymmetry near one of said extremities in each rung, the dissymmetrical extremities being alternately opposite in successive rungs, and a series of periodically spaced baffles fixed to said back plate, each baflle being disposed between two successive rungs.

12. A ladder-type delay line, comprising support means having a plane surface, a series of periodically spaced rungs having two extremities bent to be fixed to the plane surface of said support means, the shape of said rungs having, with respect to the plane of longitudinal symmetry of said line, a dissymmetry near one of said extremities in each rung, the dissymmetrical extremities being alternately opposite in successive rungs, and a series of bailies each extending between two adjacent rungs.

13. A ladder-type delay line, comprising support means having a plane surface, a series of periodically spaced rungs having two extremities bent to be fixed to the plane surface of said support means, the shape of said rungs having, with respect to the plane of longitudinal symmetry of said line, a dissymmetry near one of said extremities in each rung, the dissymmetrical extremities being alternately opposite in successive rungs, and a series of baflies each extending between two adjacent rungs and extending away from the plane surface of said support means.

14. A relatively sturdy, wide-band, ladder-type delay line operable at relatively high frequencies, comprising spaced support means, a plurality of periodically spaced delay elements each provided with two spaced extremities which are supported on said spaced support means, said delay elements being provided with means to decrease the dispersion characteristics of the delay line, said means being constituted by deformations in the otherwise relatively substantially straight shape of the delay line elements.

15. A ladder-type delay line, comprising support means, a plurality of periodically spaced delay elements each provided with two extremities which are securely supported by said support means, the shape of said delay elements having, with respect to the longitudinal plane of symmetry of said line, a dissymmetry near one of the extremities in each delay element, the dissymmetrical extremities being disposed alternately on opposite sides of said longitudinal plane of symmetry in successive rungs.

16. A ladder-type delay line, comprising support means, a series of periodically spaced rungs having both extremities thereof fixed to said support means, each of said rungs being substantially rectilinear over a major part of the length thereof and being provided near one extremity thereof with a deformed portion, the deformed portions being located on successive rungs on alternate extremities thereof so that the deformed portion of one rung approaches more closely the substantially rectilinear part at the extremitiy of an adjacent rung than the substantially rectilinear part of the said one rung.

17. In a ladder-type delay line having a plane of longitudinal symmetry and including support means, a series of periodically spaced delay elements with two extremities which are fixed to said support means, the improvement essentially consisting of a dissymmetry, with respect to the plane of longitudinal symmetry of said line, near one of said extremities in each delay element.

18. In a ladder-type delay line having a plane of longitudinal symmetry and including support means, a series of periodically spaced delay elements with two extremities which are fixed to said support means, the improvement essentially consisting of a dissymmetry, with respect to the plane of longitudinal symmetry of said line, near one of said extremities in each delay element, the dissymmetrical extremities being disposed on alternately opposite sides with respect to said plane of longitudinal symmetry in successive delay elements.

19. A ladder-type delay line, comprising support means, a series of periodically spaced delay elements having both extremities thereof fixed to said support means, each of said delay elements being substantially rectilinear over a major part of the length thereof and being provided near one extremity thereof with a deformed portion, the deformed portions being located on successive delay elements on alternate extremities thereof so that the deformed portion of one delay element approaches more closely the substantially rectilinear part at the extremity of an adjacent delay element than the substantially rectilinear part of the said one delay element.

20. A relatively sturdy, wide-band, ladder-type delay line, operable at relatively high frequencies, comprising support means, a plurality of periodically spaced delay elements each provided with a substantially linear portion and with extremities which are rigidly supported on said support means, said delay elements being provided with means to decrease the dispersion characteristics thereof which means are constituted by deformations adjoining the linear portions and extending toward the linear portion of an adjacent delay element.

References Cited UNITED STATES PATENTS 2,730,678 1/1956 Dohler 33331 2,823,332 2/ 1958 Fletcher 315--3.5 2,888,595 5/ 1959 Warnecke 315-35 2,890,384 6/1959 Dench 333-31 2,920,227 1/ 1960 Dohler 315-3.5 2,922,918 1/1960 Wasserman 315-3.5 2,942,142 6/1960 Dench 333-3 1 2,956,204 10/1960 Dohler 333-3 1 3,241,091 3/ 1966 Laures 33331 HERMAN KARL SAALBACH, Primary Examiner.

C. BARAFF, Assistant Examiner. 

1. A LADDER-TYPE DELAY LINE COMPRISING SUPPORT MEANS, A SERIES OF PERIODICALLY SPACED RUNGS HAVING BOTH EXTREMITIES THEREOF FIXED TO SAID SUPPORT MEANS, THE SHAPE OF SAID RUNGS HAVING, WITH RESPECT TO THE PLANE OF LONGITUDINAL 